In the bowl of a stand mixer fitted with the paddle attachment, mix the butter gradually increasing the speed. Take your time on this until the color of the butter really lightens up and is whipped. Add in the powdered sugar and slowly begin to mix the butter and sugar together. Starting slow will help avoid a powdered sugar mess. Mix on low speed until well blended and then increase the speed to medium and beat for another 3 minutes. Add in the vanilla and cream and continue to mix on medium for 1 minute, adding more cream if needed.